Signaling for multi-link communication in a wireless local area network (wlan)

ABSTRACT

This disclosure provides systems, methods, and apparatus, including computer programs encoded on computer-readable media, for signaling between an access point (AP) multi-link device (MLD) and a non-AP MLD that support multi-link communication in a wireless local area network (WLAN). In some implementations, a multi-link association may include a first link (referred to as an anchor link) and one or more other links (referred to as auxiliary links). The signaling may include control information to activate or deactivate auxiliary links dynamically based on communication load, throughput requirements, or quality of service (QoS). The signaling also may include requests, acknowledgments, or negotiation regarding multi-link connections. Furthermore, signaling and timing information may be used to coordinate when auxiliary links are used for communication or when to promote an auxiliary link to an anchor link.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present Application for Patent is a Continuation of U.S. patentapplication Ser. No. 16/915,983 filed Jun. 29, 2020, entitled “SIGNALINGFOR MULTI-LINK COMMUNICATION IN A WIRELESS LOCAL AREA NETWORK (WLAN)”,which claims priority to U.S. Provisional Patent Application No.62/869,546 filed Jul. 1, 2019, entitled “SIGNALING FOR MULTI-LINKCOMMUNICATION IN A WIRELESS LOCAL AREA NETWORK (WLAN),” each of whichare assigned to the assignee hereof and each of which are expresslyincorporated by reference herein.

TECHNICAL FIELD

This disclosure relates generally to the field of wirelesscommunication, and more specifically, to multi-link communication in awireless local area network (WLAN).

DESCRIPTION OF THE RELATED TECHNOLOGY

A wireless local area network (WLAN) may be formed by one or more accesspoints (APs) that provide a shared wireless communication medium for useby a number of client devices also referred to as stations (STAs). Thebasic building block of a WLAN conforming to the Institute of Electricaland Electronics Engineers (IEEE) 802.11 family of standards is a BasicService Set (BSS), which is managed by an AP. Each BSS is identified bya Basic Service Set Identifier (BSSID) that is advertised by the AP. AnAP periodically broadcasts beacon frames so that a STA within wirelessrange of the AP can establish an association with the WLAN.

A STA may have a wireless connection (referred to as a wirelessassociation, or just “association”) when it has authenticated andestablished a wireless session with the AP. Devices in a WLAN may sharecontrol information to maintain or share status. Recently, the IEEE isconsidering new features and new connectivity protocols to improveservice speed and throughput. There is an opportunity to add or improveaspects of a WLAN as the communication protocols evolve.

SUMMARY

The systems, methods, and devices of this disclosure each have severalinnovative aspects, no single one of which is solely responsible for thedesirable attributes disclosed herein.

One innovative aspect of the subject matter described in this disclosurecan be implemented as a method performed by a multi-link device (MLD)for wireless communication. The method may include establishing amulti-link association between an access point (AP) MLD and a non-APMLD. The multi-link association may include a first link between a firststation (STA) interface of the non-AP MLD and a first basic service set(BSS) of the AP MLD and further include a second link between a secondSTA interface of the non-AP MLD and a second BSS of the AP MLD. Themethod may include sending or receiving signaling, via the first link,to activate or deactivate the second link.

In some implementations, the first link is an anchor link of themulti-link association and the second link is an auxiliary link of themulti-link association.

In some implementations, the signaling includes an indication toactivate or deactivate the second link, the indication included in anaggregated control (A-Control) field of a first frame sent or receivedvia the first link.

In some implementations, the A-Control field has a specified format thatincludes a field for the indication to activate or deactivate the secondlink.

In some implementations, the specified format of the A-Control field isconsistent for each of a plurality of frames.

In some implementations, the first frame is a frame format selected froma group consisting of a management frame, a control frame, and a dataframe.

In some implementations, the first frame is selected from a groupconsisting of a request to send (RTS), a clear to send (CTS), and anacknowledgement.

In some implementations, the first frame is a power saving poll(PS-POLL) frame, a quality-of service (QoS) Null frame, or a null datapacket (NDP).

In some implementations, the first frame is first media access control(MAC) protocol data unit (MPDU).

In some implementations, the first MPDU is included in an aggregatedMPDU (A-MPDU) transmission.

In some implementations, the first MPDU includes data in a payloadportion and the indication to activate the second link in a headerportion.

In some implementations, a plurality of control parameters included inthe first frame. The plurality of control parameters may include a firstsubset of control parameters related to the first link and a secondsubset of control parameters related to the second link.

In some implementations, the first frame further includes aconfiguration for the second link.

In some implementations, establishing the multi-link associationincludes communicating a configuration of the second link. Theconfiguration may indicate one or more parameters selected from a groupconsisting of bandwidth, wireless channel, transmission rate, andfrequency band.

In some implementations, the indication is included in a multi-linkcontrol field.

In some implementations, the indication includes timing informationrelated when to activate or deactivate the second link.

In some implementations, the timing information includes a time offsetrelative to a start or end of the first frame.

In some implementations, the timing information includes a time valuebased on a timer synchronized at the AP MLD and the non-AP MLD.

In some implementations, the timer is synchronized for the first link,the second link, or both the first and second links.

In some implementations, the method may include determining a targetwake time (TWT) service period (SP) for the second link and activatingthe second link during the TWT SP.

In some implementations, establishing the multi-link associationincludes communicating multi-link capability parameters between the APMLD and the non-AP MLD.

In some implementations, the multi-link capability parameters include atleast a first value indicating a warm up time associated with a radio toactivate the second link by the non-AP MLD.

In some implementations, the method may include determining a delay orinitial data padding for a communication on the second link for useimmediately after activating the second link and before communicatingdata via the second link.

In some implementations, the multi-link capability parameters include adynamic link activation time associated with adding a new auxiliary linkto the multi-link association.

In some implementations, the AP MLD includes non-colocated APs.

In some implementations, the first link is in a first band and thesecond link is in a second band.

In some implementations, the first link is in a first channel of a firstband and the second link is in a second channel of the first band.

In some implementations, the first link includes a first set of spatialstreams and the second link includes a second set of spatial streams.

In some implementations, the method includes signaling, via the firstlink, a target beacon transmission time (TBTT) of the second link.

In some implementations, the non-AP MLD is a single radio client that iscapable of using a multi-link association by switching a single radio ofthe non-AP MLD from the first link to the second link when the secondlink is activated.

In some implementations, the indication to activate the second link istransmitted via a non-multiple-input-multiple-output (non-MIMO)communication via the first link. The method may include deactivatingthe second link or the first link during a MIMO communication via theother one of the second link or the first link.

In some implementations, the method includes designating one of thefirst link or the second link as an anchor link of the multi-linkassociation regardless of which link was used to establish themulti-link association.

In some implementations, the method includes changing a designation ofthe anchor link to another one of the first link or the second link,wherein the anchor link is a link that is maintained for signalingregarding the multi-link association and other links are designated asauxiliary links that can be dynamically activated using signaling viathe anchor link.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented as a method for wireless communication bya non-AP multi-link device (MLD). The method may include establishing amulti-link association with an access point (AP) MLD. The multi-linkassociation may include a first link between a first station (STA)interface of the non-AP MLD and a first basic service set (BSS) of theAP MLD and may further include a second link between a second STAinterface of the non-AP MLD and a second BSS of the AP MLD. The methodmay include determining that the second link can be deactivated based,at least in part, on an amount of traffic for the second link beingbelow a threshold amount. The method may include deactivating the secondlink by causing the second STA interface to enter a doze state.

In some implementations, the method may include receiving signaling, viathe first link, to activate the second link. The method may includeactivating the second link by causing the second STA interface to enteran awake state.

In some implementations, the signaling to activate the second linkincludes a traffic indication from the AP MLD that indicates buffereddownlink traffic for the second link.

In some implementations, activating the second link includesdeactivating the first link by causing the first STA interface to entera doze state, switching one or more antennas from a first connection tothe first STA interface to a second connection to the second STAinterface, and causing the second STA interface to enter the awake statefor multi-input-multiple-output (MIMO) communication using multipleantennas including the one or more antennas.

In some implementations, the first link is designated as an anchor linkand the second link is designated as an auxiliary link during themulti-link association.

In some implementations, the method may include, after the multi-linkassociation, changing the designation of the anchor link from the firstlink to the second link. The method may include deactivating the firstlink by causing the first STA to enter a doze state.

In some implementations, changing the designation includes implicitlydesignating the second link as the anchor link by activating the secondlink and deactivating the first link.

In some implementations, changing the designation includes explicitlydesignating the second link as the anchor link by sending signaling tothe AP MLD.

In some implementations, the method may include receiving signaling,from the AP MLD, that indicates buffered downlink traffic for the non-APMLD. The method may include determining one or more links of themulti-link association to activate for communication with the AP MLDbased, at least in part, on an amount of the buffered downlink traffic.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented as a computer-readable medium havingstored therein instructions which, when executed by a processor, causesthe processor to perform any one of the above methods.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented as an apparatus having an interface forcommunicating via a wireless local area network and a processor. Theprocessor may be configured to perform any one of the above methods.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented as system including means for implementingany one of the above methods.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented as an apparatus having a first STAinterface configured to establish a first link between the first STAinterface and a first BSS of an AP MLD as part of a multi-linkassociation. The apparatus may have a second STA interface configured toestablish a second link between the second STA interface and a secondBSS of the AP MLD as part of the multi-link association. The apparatusmay have a processor configured to output or obtain signaling, via thefirst STA interface, the signaling including an indication to activateor deactivate the second link.

In some implementations, the first link is an anchor link of themulti-link association and the second link is an auxiliary link of themulti-link association.

In some implementations, the indication to activate or deactivate thesecond link is included in an aggregated control (A-Control) field of afirst frame sent or received via the first link.

In some implementations, the A-Control field has a specified format thatincludes a field for the indication to activate or deactivate the secondlink.

In some implementations, the specified format of the A-Control field isconsistent for each of a plurality of frames.

In some implementations, the first frame is a frame format selected froma group consisting of a management frame, a control frame, and a dataframe.

In some implementations, the first frame is selected from a groupconsisting of a request to send (RTS), a clear to send (CTS), and anacknowledgement.

In some implementations, the first frame is a power saving poll(PS-POLL) frame, a quality-of service (QoS) Null frame, or a null datapacket (NDP).

In some implementations, the first frame is first media access control(MAC) protocol data unit (MPDU).

In some implementations, the first MPDU is included in an aggregatedMPDU (A-MPDU) transmission.

In some implementations, the first MPDU includes data in a payloadportion and the indication to activate the second link in a headerportion.

In some implementations, the indication is included in a multi-linkcontrol field.

In some implementations, the indication includes timing informationrelated when to activate or deactivate the second link.

In some implementations, the processor may be configured to determine atarget wake time (TWT) service period (SP) for the second link andactivate the second link during the TWT SP.

In some implementations, the processor is further configured tocommunicate multi-link capability parameters to the AP MLD via the firstSTA interface or the second STA interface as part of the multi-linkassociation.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented as a wireless communication device. Thewireless communication device may include a plurality of STA interfaces,at least one processor, and at least one memory communicatively coupledwith the at least one processor and storing processor-readable codethat, when executed by the at least one processor, causes the wirelesscommunication device to perform any of the above-mentioned methods. Forexample, the processor-readable code that, when executed by the at leastone processor, may cause the wireless communication device to establisha multi-link association with an AP MLD. The multi-link association mayinclude a first link between a first STA interface of the plurality ofSTA interfaces and a first BSS of the AP MLD and may further include asecond link between a second STA interface of the plurality of STAinterfaces and a second BSS of the AP MLD. The processor-readable codethat, when executed by the at least one processor, causes the wirelesscommunication device to send or receive signaling, via the first link,to activate or deactivate the second link

Another innovative aspect of the subject matter described in thisdisclosure can be implemented as a mobile device. The mobile device mayinclude a wireless communication device having a plurality of STAinterfaces, at least one processor, and at least one memorycommunicatively coupled with the at least one processor and storingprocessor-readable code that, when executed by the at least oneprocessor, causes the wireless communication device to perform any ofthe above-mentioned methods. For example, the processor-readable codethat, when executed by the at least one processor, may cause thewireless communication device to establish a multi-link association withan AP MLD. The multi-link association may include a first link between afirst STA interface of the plurality of STA interfaces and a first BSSof the AP MLD and may further include a second link between a second STAinterface of the plurality of STA interfaces and a second BSS of the APMLD. The processor-readable code that, when executed by the at least oneprocessor, causes the wireless communication device to send or receivesignaling, via the first link, to activate or deactivate the secondlink. The mobile device may include at least one transceiver coupled tothe wireless communication device, at least one antenna coupled to theat least one transceiver to wirelessly transmit signals output from theat least one transceiver and to wirelessly receive signals for inputinto the at least one transceiver and a housing that encompasses thewireless communication device, the at least one transceiver and at leasta portion of the at least one antenna.

Details of one or more implementations of the subject matter describedin this disclosure are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages will becomeapparent from the description, the drawings and the claims. Note thatthe relative dimensions of the following figures may not be drawn toscale.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a pictorial diagram of an example wireless communicationnetwork.

FIG. 2A shows a pictorial diagram of a multi-link association.

FIG. 2B shows a pictorial diagram of an example wireless communicationnetwork that implements multi-link communication.

FIG. 3A shows an example protocol data unit (PDU) usable forcommunications between an access point (AP) and a station (STA).

FIG. 3B shows an example field in the PDU of FIG. 3A.

FIG. 4A shows a pictorial diagram of example signaling to activate alink of a multi-link association using one or more individuallyaddressed frames.

FIG. 4B shows a pictorial diagram of example signaling to activate alink of a multi-link association using a broadcast frame.

FIG. 4C shows a pictorial diagram of example signaling regarding targetwake time (TWT) coordination in multi-link communication.

FIG. 4D shows a pictorial diagram of example signaling regarding timingto activate a link of a multi-link association.

FIG. 4E shows a pictorial diagram of example signaling to activate alink of a multi-link association using a preamble indicator.

FIG. 5A shows a pictorial diagram of example signaling for downlinkcommunication in a multi-link association with spatial multiplexing.

FIG. 5B shows a pictorial diagram of example signaling for uplinkcommunication in a multi-link association with spatial multiplexing.

FIG. 5C shows a pictorial diagram of an enhanced multi-link single radio(eMLSR) technique for a multi-link device (MLD) that has a single radiowith multiple available antennas.

FIG. 6A shows a diagram of an example physical layer convergenceprocedure (PLCP) protocol data unit (PPDU) frame.

FIG. 6B shows a diagram of an example aggregated media access control(MAC) protocol data unit (A-MPDU) frame.

FIG. 7 shows a flowchart illustrating an example process for managing amulti-link association.

FIG. 8 shows a diagram of an example MAC frame with an AggregatedControl (A-Control) field.

FIG. 9A shows a first example of an A-Control field that includescontrol parameters for one or more links of a multi-link association.

FIG. 9B shows another example of an A-Control field that includescontrol parameters for one or more links of a multi-link association.

FIG. 9C shows an example of explicit indicators for multi-linkaggregated control parameters.

FIG. 9D shows another example of an A-Control field with controlparameters for one or more links of a multi-link association.

FIG. 9E shows an example of an A-Control field with control parametersfor multiple links without using delimiters.

FIG. 10 depicts an example message flow diagram associated withmulti-link communication.

FIG. 11 shows a block diagram of an example wireless communicationdevice.

FIG. 12A shows a block diagram of an example AP.

FIG. 12B shows a block diagram of an example STA.

FIG. 13 depicts a conceptual diagram of an example frame for multi-linkcommunication.

FIG. 14 shows a flowchart illustrating an example process for connectingto services.

FIG. 15 shows a block diagram of an example wireless communicationdevice for use in wireless communication.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

The following description is directed to certain implementations for thepurposes of describing innovative aspects of this disclosure. However, aperson having ordinary skill in the art will readily recognize that theteachings herein can be applied in a multitude of different ways. Thedescribed implementations can be implemented in any device, system ornetwork that is capable of transmitting and receiving radio frequency(RF) signals according to one or more of the Institute of Electrical andElectronics Engineers (IEEE) 802.11 standards, the IEEE 802.15standards, the Bluetooth® standards as defined by the Bluetooth SpecialInterest Group (SIG), or the Long Term Evolution (LTE), 3G, 4G or 5Gstandards, among others. The described implementations can beimplemented in any device, system or network that is capable oftransmitting and receiving RF signals according to one or more of thefollowing technologies or techniques: code division multiple access(CDMA), time division multiple access (TDMA), frequency divisionmultiple access (FDMA), orthogonal frequency division multiple access(OFDMA), single-user (SU) multiple-input-multiple-output (MIMO) andmulti-user (MU) MIMO. The described implementations also can beimplemented using other wireless communication protocols or RF signalssuitable for use in one or more of a wireless personal area network(WPAN), a wireless local area network (WLAN), a wireless wide areanetwork (WWAN), or an internet of things (IoT) network.

A wireless local area network (WLAN) in a home, apartment, business, orother areas may include one or more WLAN devices that share a wirelesscommunication medium. A station (STA) is a logical entity in a WLANdevice and represents an addressable instance of a media access control(MAC) and physical layer (PHY) interface to the wireless communicationmedium. An access point (AP) is a WLAN device that includes a STAinterface as well as a distribution system access function. Often theshorthand terms “AP” and “STA” may been used to distinguish betweenthose WLAN devices that include the distribution system access functionand those that do not, respectively. The basic building block of a WLANconforming to the Institute of Electrical and Electronics Engineers(IEEE) 802.11 family of standards is a Basic Service Set (BSS), which ismanaged by an AP. Each BSS includes the AP and those STAs that areassociated with the AP.

Some WLAN devices may operate multiple STA interfaces, such as a firstSTA interface and a second STA interface in the same device. Recently,the IEEE is discussing techniques for multi-link association. Amulti-link device (MLD) is a type of WLAN device that includes multipleinterfaces and is capable of establishing a multi-link association withanother MLD. An AP MLD may operate multiple BSSs and supports amulti-link association with a non-AP MLD. Other terms may be envisionedfor the various types of MLDs. For example, an AP MLD also may bereferred to as an AP entity or a multi-link access point (ML-AP). Anon-AP MLD also may be referred to as non-AP entity, a STA MLD, or amulti-link station (ML-STA). For clarity, this disclosure refers to themulti-link capable devices as either an AP MLD or a non-AP MLD. In someimplementations, an AP MLD may operate a first BSS in a first frequencyband and a second BSS in a second frequency band. The AP MLD and anon-AP MLD may establish a multi-link association in which multiplelinks are enabled between the AP MLD and the non-AP MLD. Each link ofthe multi-link association may be between a different STA interface of anon-AP-MLD in a corresponding BSS of the AP MLD. For example, a non-APMLD may establish a first link to the first BSS using a first STAinterface of the non-AP MLD and may establish a second link to thesecond BSS using a second STA interface of the non-AP MLD. The multiplelinks of the multi-link association may be established using differentchannels, frequency bands, or spatial streams, among other examples.

A multi-link association may streamline the establishment of multiplelinks. A multi-link association also may be referred to as a multi-linksetup. The AP MLD and the non-AP MLD may exchange the setup and responseframes via a first link to provision or configure multiple links of themulti-link association. The multi-link setup via the first link mayenable the multiple STAs of the non-AP MLD to concurrently associatewith the different BSSs operated by the AP MLD. Thereafter, one link(which may be the first link or any of the other links established inthe multi-link setup) may be maintained as an active connection forsignaling or other basic BSS operations related to the multi-linkassociation. In some implementations, the link that is maintained forsignaling or other basic BSS operations may be referred to as an anchorlink, main link, primary link, master link, control link, or other termsto differentiate that link from other links of the multi-linkassociation. From time to time, the AP MLD and non-AP MLD may changewhich link is currently the anchor link for the multi-link association.The other links of the multi-link association may be referred to asauxiliary links, non-anchor links, secondary links, subordinate links,dynamic links, or other such terms. For clarity, the terms “anchor link”and “auxiliary link” are used in this disclosure.

Multi-link communication may enable a larger amount of data throughputbetween the MLDs because multiple links may concurrently transmit datawhen they are activated. Each link may be associated with a differentradio frequency (RF) chain of the MLD and each RF chain may consumepower when it is activated for multi-link communication. Therefore, whenless data is available it may desirable to deactivate some auxiliarylinks to reduce power consumption. Having the ability to dynamicallyactivate or deactivate auxiliary links may provide greater flexibilityfor power saving and throughput.

This disclosure provides systems, methods, and apparatus, includingcomputer programs encoded on computer-readable media, for multi-linkcommunication. Various aspects relate generally to signaling to managethe activation or deactivation of auxiliary links of a multi-linkassociation. The signaling may enable that AP MLD and the non-AP MLD toselect which links to activate for communication of traffic betweenthem. For example, the activation or deactivation of an auxiliary linkmay be signaled by explicit messaging, broadcast messaging, or as partof a data packet on the anchor link. The activation of an auxiliary linkmay be based on an amount or type of data buffered to send from an APMLD to a non-AP MLD, or vice versa. An AP MLD may set up an anchor linkto aid the non-AP MLD with power saving capability, throughput,reliability, or data separation. For example,

In accordance with this disclosure, signaling regarding multi-linkassociations may be sent or received on the anchor link. In someimplementations, an AP MLD may indicate that it supports a multi-linkassociation in the beacon frames or other discovery information that theAP MLD broadcasts so that the non-AP MLD can determine that the AP MLDsupports multi-link association. When the AP MLD and the non-AP MLDestablishes a multi-link association, a traffic identifier (TID) may bemapped to one or more links established by the multi-link association.In some implementations, each link in the multi-link association may beidentified by a link identifier (Link ID) or other indicator todistinguish the links.

An auxiliary link may be “enabled” for communication when a TID ismapped to it. However, even though the auxiliary link is enabled, thenon-AP MLD or the AP MLD may dynamically activate or deactivate theauxiliary link based on the availability of traffic associated with theTID. Furthermore, one or more auxiliary links may be dynamicallyactivated or deactivated based on throughput requirements, speed, orquality of service. When the auxiliary link is activated, the STAinterface for that link may be in an awake state such that it is fullypowered and able to transmit or receive data. When the auxiliary link isdeactivated, the STA interface for that link may be in a doze state inwhich the STA interface consumes very low power and is unable totransmit or receive data. In some implementations, activation of anauxiliary link also may include enabling the auxiliary link by mapping aTID to that link. Furthermore, an auxiliary link may be disabled anddeactivated when there is no TID mapped to that link.

Some aspects more specifically relate to power saving techniques thatinvolve activation or deactivation of auxiliary links. The signalingdescribed in this disclosure may be used to realize power savings in anon-AP MLD. For example, a non-AP MLD may reduce the quantity of RFchains that would otherwise be activated and idle. In someimplementations, the MLDs may utilize signaling on the anchor link tocommunicate status or information that would otherwise be signaledseparately on the auxiliary links. In some implementations, thesignaling may include timing information to coordinate the timing ofcommunication via an auxiliary link or the timing for activation of theauxiliary link. In some implementations, an AP MLD may providesufficient time for a non-AP MLD to energize an RF chain for anauxiliary link as part of the activation before transmitting data on theauxiliary link. Referred to as a “warm up” time, there may be a delayassociated with preparing a second RF chain at the non-AP MLD. Signalingmay ensure that sufficient warm up time is provided so that the non-APMLD is ready to receive communication before the AP MLD sendscommunication on the auxiliary link.

In some implementations, an anchor link may be set up on a lowerfrequency band for better coverage and reliability while an auxiliarylink may be set up on a higher frequency band so that the auxiliary linkcan be activated for greater throughput when there is data to send. Insome implementations, the auxiliary link may be used as an on-demanddedicated data channel. And because signaling or management frames maybe communicated via the anchor link there may be a greater efficiency ofcommunication on the dedicated data channel. In some implementations,the link that is designated as the anchor link can be changeddynamically based on the link on which the non-AP MLD indicates it isawake or present. In some implementations, an AP MLD may signal theavailability of traffic to send to the non-AP MLD. The non-AP MLD mayindicate which link or links (among those mapped to a TID for thattraffic) to activate for the transmission of the traffic.

In legacy technical standards, control information may be structuredaccording to a fixed length field and defined bit locations fordifferent control parameters. More recently, the quantity and type ofcontrol parameters has increased, making legacy control formatsinsufficient. Furthermore, the fixed length of legacy control formatslimits the type and quantity of control parameters that can be includedin a frame. To provide some greater flexibility, an aggregated control(A-Control) field may include multiple control parameters. Each controlparameter (sometimes also referred to as a control field or a controlsubfield) may include a control identifier (Control ID) and a controlvalue. In some implementations, a device may operate simultaneously orat different times with multiple links (multi-link, multi-channel, ormulti-bands). The A-Control field may be structured to includemulti-link control information. For example, the A-Control field mayinclude a first subset of control parameters for an anchor link and asecond subset of control parameters for an auxiliary link. For example,the A-Control field may include signaling for indicating controlinformation that governs or helps the functionality of a link. As anexample, the signaling may include signaling for dynamic activation ordeactivation of various auxiliary links.

This disclosure includes a variety of techniques for signalingmulti-link control information. For example, each of the links may beidentified using explicit signaling or implicitly based on one or moreof the structure of the A-Control field, certain bit settings in framesthat carry the A-Control field, or the link (such as the channel orband) at which the frame is exchanged. Therefore, the identifier of thelink of interest may be determined from the A-Control field or the framethat carries the A-Control field. For example, a link may be identifiedby certain bits preceding each set of Control parameters. In anotherexample, the link may be identified by certain bits contained in theframe that carries the A-Control field. In some implementations, theA-Control field may contain a link identifier or delimiter to signal thebeginning or end of a subset of control parameters for each link. Insome implementations, the MPDU may be a Management frame containing aninformation element (IE) identifying the link of interest. In someimplementations, the link identifier may be contained in the QoS Controlfield, or any other field of the MAC header that precedes the fieldcontaining the A-Control field. The A-Control field described in thisdisclosure may be included in any type of frame, including a managementframe, a data frame or a control frame. The A-Control field also may beincluded in a PPDU that does not contain a Data field. For example, theA-Control field may be included as a field of the PHY header of the PPDUwithout having a data field. In some implementations, the A-Controlfield may be included in an MPDU that is part of an A-MPDU with multipleframes. In some implementations, the A-Control field may be included ina payload of a null frame (such as a quality-of-service, QoS, Null frameor a null data packet (NDP)).

In some implementations, the AP MLD or the non-AP MLD may wake up oractivate an auxiliary link that was previously deactivated usingsignaling described herein. Furthermore, the activation of an auxiliarylink also may include activation of spatial multiplexing (SM) on theauxiliary link. SM power saving may be implemented for one or more linksof a multi-link association. SM power saving refers to the use ofsingle-stream communication for basic signaling and lower powerconsumption. At times when more data is communicated, additional RFchains may be activated to perform processing of different SM streams.In a multi-link association, the SM power saving may be used on ananchor link. When there is data to transmit or receive, an MLD mayactivate additional RF chains (for either or both the anchor link orauxiliary links) to take advantage of spatial multiplexing. When thereis no data (or little data) to transmit or receive, the MLD maydeactivate RF chains to conserve power.

Particular implementations of the subject matter described in thisdisclosure can be implemented to realize one or more of the followingpotential advantages. A wireless communication device may avoid havingmultiple RF chains activated until they are needed. By reducing thenumber of RF chains that are activated, power saving may be realized atthe wireless communication device. The signaling may provide better timecoordination for auxiliary links based on warm up time used by a non-APMLD to activate an RF chain for an auxiliary link.

FIG. 1 shows a pictorial diagram of an example wireless communicationnetwork. FIG. 1 includes a block diagram of an example wirelesscommunication network 100. According to some aspects, the wirelesscommunication network 100 can be an example of a wireless local areanetwork (WLAN) such as a Wi-Fi network (and will hereinafter be referredto as WLAN 100). For example, the WLAN 100 can be a network implementingat least one of the IEEE 802.11 family of standards (such as thatdefined by the IEEE 802.11-2016 specification or amendments thereofincluding, but not limited to, 802.11aa, 802.11ah, 802.11ad, 802.11aq,802.11ay, 802.11ax, 802.11az, 802.11ba and 802.11be). The WLAN 100 mayinclude numerous wireless communication devices such as an access point(AP) 102 and multiple stations (STAs) 104 that have a wirelessassociation with the AP 102. In addition, there may be STAs (not shown)that do not have a wireless association with the AP 102. While only oneAP 102 is shown, the WLAN network 100 also can include multiple APs 102.

Each of the STAs 104 also may be referred to as a mobile station (MS), amobile device, a mobile handset, a wireless handset, an access terminal(AT), a user equipment (UE), a subscriber station (SS), or a subscriberunit, among other possibilities. The STAs 104 may represent variousdevices such as mobile phones, personal digital assistant (PDAs), otherhandheld devices, netbooks, notebook computers, tablet computers,laptops, display devices (for example, TVs, computer monitors,navigation systems, among others), music or other audio or stereodevices, remote control devices (“remotes”), printers, kitchen or otherhousehold appliances, key fobs (for example, for passive keyless entryand start (PKES) systems), among other possibilities.

A single AP 102 and an associated set of STAs 104 may be referred to asa BSS, which is managed by the respective AP 102. FIG. 1 additionallyshows an example coverage area 108 of the AP 102, which may represent abasic service area (BSA) of the WLAN 100. The BSS may be identified tousers by a service set identifier (SSID), as well as to other devices bya basic service set identifier (BSSID), which may be a media accesscontrol (MAC) address of the AP 102. The AP 102 periodically broadcastsbeacon frames (“beacons”) including the BSSID to enable any STAs 104within wireless range of the AP 102 to establish a respectivecommunication link 106 (hereinafter also referred to as a “Wi-Fi link”),or to maintain a communication link 106, with the AP 102. For example,the beacons can include an identification of a primary channel used bythe respective AP 102 as well as a timing synchronization function forestablishing or maintaining timing synchronization with the AP. The AP102 may provide access to external networks to various STAs 104 in theWLAN via respective communication links 106. To establish acommunication link 106 with an AP 102, each of the STAs 104 isconfigured to perform passive or active scanning operations (“scans”) onfrequency channels in one or more frequency bands (for example, the 2.4GHz, 5 GHz, 6 GHz or 60 GHz bands). To perform passive scanning, a STA104 listens for beacons, which are transmitted by respective APs 102 ata periodic time interval referred to as the target beacon transmissiontime (TBTT) (measured in time units (TUs) where one TU may be equal to1024 microseconds (μs)). To perform active scanning, a STA 104 generatesand sequentially transmits probe requests on each channel to be scannedand listens for probe responses from APs 102. Each STA 104 may beconfigured to identify or select an AP 102 with which to associate basedon the scanning information obtained through the passive or activescans, and to perform authentication and association operations toestablish a communication link 106 with the selected AP 102. The AP 102assigns an association identifier (AID) to the STA 104 at theculmination of the association operations, which the AP 102 uses totrack the STA 104.

FIG. 1 additionally shows an example coverage area 108 of the AP 102,which may represent a basic service area (BSA) of the WLAN 100. As aresult of the increasing ubiquity of wireless networks, a STA 104 mayhave the opportunity to select one of many BSSs within range of the STAor to select among multiple APs 102 that together form an extendedservice set (ESS) including multiple connected BSSs. An extended networkstation associated with the WLAN 100 may be connected to a wired orwireless distribution system that may allow multiple APs 102 to beconnected in such an ESS. As such, a STA 104 can be covered by more thanone AP 102 and can associate with different APs 102 at different timesfor different transmissions. Additionally, after association with an AP102, a STA 104 also may be configured to periodically scan itssurroundings to find a more suitable AP 102 with which to associate. Forexample, a STA 104 that is moving relative to its associated AP 102 mayperform a “roaming” scan to find another AP 102 having more desirablenetwork characteristics such as a greater received signal strengthindicator (RSSI) or a reduced traffic load.

In some cases, STAs 104 may form networks without APs 102 or otherequipment other than the STAs 104 themselves. One example of such anetwork is an ad hoc network (or wireless ad hoc network). Ad hocnetworks may alternatively be referred to as mesh networks orpeer-to-peer (P2P) networks. In some cases, ad hoc networks may beimplemented within a larger wireless network such as the WLAN 100. Insuch implementations, while the STAs 104 may be capable of communicatingwith each other through the AP 102 using communication links 106, STAs104 also can communicate directly with each other via direct wirelesslinks 109. Additionally, two STAs 104 may communicate via a directcommunication link 109 regardless of whether both STAs 104 areassociated with and served by the same AP 102. In such an ad hoc system,one or more of the STAs 104 may assume the role filled by the AP 102 ina BSS. Such a STA 104 may be referred to as a group owner (GO) and maycoordinate transmissions within the ad hoc network. Examples of directwireless links 109 include Wi-Fi Direct connections, connectionsestablished by using a Wi-Fi Tunneled Direct Link Setup (TDLS) link, andother P2P group connections.

The APs 102 and STAs 104 may function and communicate (via therespective communication links 106) according to the IEEE 802.11 familyof standards (such as that defined by the IEEE 802.11-2016 specificationor amendments thereof including, but not limited to, 802.11aa, 802.11ah,802.11aq, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba and802.11be). These standards define the WLAN radio and baseband protocolsfor the PHY and medium access control (MAC) layers. The APs 102 and STAs104 transmit and receive wireless communications (hereinafter alsoreferred to as “Wi-Fi communications”) to and from one another in theform of physical layer convergence protocol (PLCP) protocol data units(PPDUs).

Each of the frequency bands may include multiple sub-bands or frequencychannels. For example, PPDUs conforming to the IEEE 802.11n, 802.11acand 802.11ax standard amendments may be transmitted over the 2.4 and 5GHz bands, each of which is divided into multiple 20 MHz channels. Assuch, these PPDUs are transmitted over a physical channel having aminimum bandwidth of 20 MHz, but larger channels can be formed throughchannel bonding. For example, PPDUs may be transmitted over physicalchannels having bandwidths of 40 MHz, 80 MHz, 160 or 520 MHz by bondingtogether multiple 20 MHz channels.

Each PPDU is a composite structure that includes a PHY preamble and apayload in the form of a PLCP service data unit (PSDU). For example, thePSDU may include a PLCP preamble and header as well as one or more MACprotocol data units (MPDUs). The information provided in the PHYpreamble may be used by a receiving device to decode the subsequent datain the PSDU. In instances in which PPDUs are transmitted over a bondedchannel, the preamble fields may be duplicated and transmitted in eachof the multiple component channels. The PHY preamble may include both alegacy portion (or “legacy preamble”) and a non-legacy portion (or“non-legacy preamble”). The legacy preamble may be used for packetdetection, automatic gain control and channel estimation, among otheruses. The legacy preamble also may generally be used to maintaincompatibility with legacy devices. The format of, coding of, andinformation provided in the non-legacy portion of the preamble is basedon the particular IEEE 802.11 protocol to be used to transmit thepayload.

FIG. 2A shows a pictorial diagram of a multi-link association. A firstwireless communication device (such as an AP entity, or AP) mayhereinafter be referred to as an AP MLD 110. The AP-MLD 110 may becapable of establishing a multi-link association with a second wirelesscommunication device (such as a non-AP entity, or STA) which mayhereinafter be referred to as a non-AP MLD 120. In some implementations,the non-AP MLD 120 may be an IoT device. The non-AP MLD 120 may becapable of establishing the multi-link association with the AP-MLD 110.

FIG. 2A shows a first link (referred to as an anchor link 132) and asecond link (referred to as an auxiliary link 134) between the AP MLD110 and the non-AP MLD 120. Although only one auxiliary link 134 isshown in FIG. 2A, some implementations may include multiple auxiliarylinks (not shown). The anchor link 132 may be used for control andsignaling between the AP MLD 110 and the non-AP MLD 120.

The different links 132 and 134 may share a common associationidentifier (AID). In some implementations, the AP MLD 110 may providedifferent association identifiers (AIDs) for the different links 132 and134 to the non-AP MLD even though the multi-link association isconsidered one common association. For example, the AP MLD may assign afirst AID for the anchor link 132 and a second AID for the auxiliarylink 134. The non-AP MLD 120 may determine whether the auxiliary link134 should be activated based on the existence of the second AID in atraffic indication map (TIM) message or other message from the AP MLD110. Alternatively, or additionally, the AP MLD 110 may assign differentLink IDs to the different links 132 and 134. The Link ID may be shorterthan a size of a traditional AID.

In accordance with this disclosure, the AP MLD 110 (or the non-AP MLD120) may selectively activate or deactivate the auxiliary link 134. Forexample, the non-AP MLD 120 may send a request or indication of datarequirements that cause the AP MLD 110 to determine that the anchor link132 is insufficient for the amount of data. Alternatively, the AP MLD110 may have downlink data to send to the non-AP MLD 120 and maydetermine to activate the auxiliary link 134 based on the amount ofdownlink data.

In some implementations, the anchor link 132 may be established on amore reliable frequency band (such as 2.4 GHz) while the auxiliary link134 may be established on a faster (but potentially less reliable)frequency band (such as the 5 GHz band or 6 GHz band). In someimplementations, the 6 GHz band may be a fully scheduled frequency band,and the anchor link 132 may be used to signal resource requirementsregarding a TID such that the AP MLD 110 and the non-AP MLD 120 canselectively activate the auxiliary link 134 when there is traffic tosend for the TID. Although described as different channels or differentbands in this disclosure, other examples of links may include spatialstreams or any combination of different channels, bands, or spatialstreams.

In some implementations, the non-AP MLD 120 may be a multi-radio devicewhich can operate on multiple channels or frequency bands concurrently.For example, the non-AP MLD 120 may have separate interfaces toconcurrently utilize the anchor link 132 and the auxiliary link 134. Theseparate interfaces may be implemented in a common chip or componenthaving separate radios for each interface. Each radio may have an RFchain connected to a one or more antennas different from another radio.When implemented as a multi-radio device, the non-AP MLD 120 may becapable of concurrently communicating via the anchor link 132 and theauxiliary link 134.

In some implementations, the non-AP MLD 120 may be a single-radiodevice. The non-AP MLD 120 may switch the radio to alternativelycommunicate via one of the links 132 and 134. The non-AP MLD 120 may bereferred to as a multi-link capable single-radio (MLSR) device. When theauxiliary link 134 is activated, the auxiliary link 134 may be promotedto become the anchor link for signaling purposes until the auxiliarylink 134 is deactivated and the original anchor link 132 is activated.Thus, anchor link may be the link that is currently activated and whichthe non-AP MLD 120 has a STA interface in an active or awake state.Those links which are associated with a STA interface in a doze statemay be designated as auxiliary links. The designation of which link isthe anchor link may be implicit based on activation of a link. In someimplementations, the AP MLD 110 and the non-AP MLD 120 may transfer ofall TID flows to a different link, and that link may be designated thatlink as the anchor link. In a multi-link association, the AP MLD 110 andthe non-AP MLD 120 may negotiate and pre-configure more than one linkfor use between them regardless of whether the non-AP MLD 120 has oneradio or multiple radios.

As stated previously, a designation of an anchor link for a multi-linkassociation may be changed. Either the AP MLD or the non-AP MLD mayimplicitly or explicitly signal a change in the multi-link associationto designate one of the links as the anchor link. When the AP MLD hasestablished multi-link associations with different non-AP MLDs, theanchor link for each non-AP MLD may be in the same wireless channel orin different wireless channels. For example, it is possible that twonon-AP MLDs associated with the same AP MLD have their respective anchorlinks in different BSSs of the AP MLD.

FIG. 2B shows a pictorial diagram of an example wireless communicationnetwork that implements multi-link communication. In FIG. 2B, the AP 102may be an AP MLD 110. The STA 104 may be a non-AP MLD 120.

The AP MLD 110 may include a multi-link communication control unit 112and a signaling generation unit 114. The multi-link communicationcontrol unit 112 may implement the multi-link association in accordancewith aspects of this disclosure. The signaling generation unit 114 mayprepare and communicate the signaling described herein. The non-AP MLD120 may include a multi-link communication control unit 122 and a signalprocessing unit 124. The multi-link communication control unit 122 mayimplement the multi-link association in accordance with aspects of thisdisclosure. In some instances, the AP MLD 110 and the non-AP MLD 120 mayexchange service discovery frames or other management frames toascertain whether both devices support the multi-link association andsignaling as described herein.

A technical standard may define formats for communications. For example,the first wireless communication device may prepare and transmit a mediaaccess control (MAC) protocol data unit (MPDU) according to astandardized format. An MPDU also may be referred to as a frame or apacket in some aspects of this disclosure. A physical convergence layer(PHY) protocol data unit (PPDU) may include one or more MPDUs. Forexample, one type of PPDU (referred to as an Aggregated MPDU, or A-MPDU)may include multiple MPDUs in a payload of the AMPDU.

FIG. 3A shows an example protocol data unit (PDU) 300 usable forcommunications between an AP and a number of STAs. For example, the PDU300 can be configured as a PPDU. As shown, the PDU 300 includes a PHYpreamble 302 and a PHY payload 304. For example, the PHY preamble 302may include a legacy portion that itself includes a legacy shorttraining field (L-STF) 306, a legacy long training field (L-LTF) 308,and a legacy signaling field (L-SIG) 310. The PHY preamble 302 also mayinclude a non-legacy portion (not shown). The L-STF 306 generallyenables a receiving device to perform automatic gain control (AGC) andcoarse timing and frequency estimation. The L-LTF 308 generally enablesa receiving device to perform fine timing and frequency estimation andalso to estimate the wireless channel. The L-SIG 310 generally enables areceiving device to determine a duration of the PDU and use thedetermined duration to avoid transmitting on top of the PDU. Forexample, the L-STF 306, the L-LTF 308 and the L-SIG 310 may be modulatedaccording to a binary phase shift keying (BPSK) modulation scheme. Thepayload 304 may be modulated according to a BPSK modulation scheme, aquadrature BPSK (Q-BPSK) modulation scheme, a quadrature amplitudemodulation (QAM) modulation scheme, or another appropriate modulationscheme. The payload 304 may generally carry higher layer data, forexample, in the form of medium access control (MAC) protocol data units(MPDUs) or an aggregated MPDU (A-MPDU).

FIG. 3B shows an example L-SIG field 310 in the PDU of FIG. 3A. TheL-SIG 310 includes a data rate field 312, a reserved bit 314, a lengthfield 316, a parity bit 318, and a tail field 320. The data rate field312 indicates a data rate (note that the data rate indicated in the datarate field 312 may not be the actual data rate of the data carried inthe payload 304). The length field 316 indicates a length of the packetin units of, for example, bytes. The parity bit 318 is used to detectbit errors. The tail field 320 includes tail bits that are used by thereceiving device to terminate operation of a decoder (for example, aViterbi decoder). The receiving device utilizes the data rate and thelength indicated in the data rate field 312 and the length field 316 todetermine a duration of the packet in units of, for example,microseconds (μs).

FIG. 4A shows a pictorial diagram 401 of example signaling to activate alink of a multi-link association using one or more individuallyaddressed frames. An AP MLD 110 and a non-AP MLD 120 may establish amulti-link association that includes configuration for a first link(Link 1, referred to as an anchor link 132) and a second link (Link 2,referred to an auxiliary link 134). The AP MLD 110 may periodicallytransmit beacon frames 410 to maintain synchronization of the variouslinks. The non-AP MLD 120 may observe the beacon frames 410 on theanchor link 132 and may or may not observe beacon frames on theauxiliary link 134. In some implementations, the non-AP MLD 120 maymaintain the auxiliary link 134 in a deactivated state 411 until itreceives signaling from the AP MLD 110 to activate the auxiliary link134 or until it has data to transmit via the auxiliary link 134. The APMLD 110 may use signaling (such as in an A-Control field) on the anchorlink 132 to activate the auxiliary link 134). For example, a first frame412 may include an A-Control field or other indicator to inform thenon-AP MLD 120 to activate the auxiliary link 134. When the auxiliarylink 134 is activated (by either the AP MLD 110 or the non-AP MLD 12),the non-AP MLD 120 may cause its STA interface for the auxiliary link134 to change from a doze state to an awake state. In someimplementations, the non-AP MLD 120 may send an acknowledgement (ACK)414 on the anchor link 132 to acknowledge the activation 413 of theauxiliary link 134. Data (such as a data frame 415) may be sent on bothlinks when they are both activated. At some point, the AP MLD 110 maysignal an instruction or indicator to for the non-AP MLD 120 todeactivate the auxiliary link 134. For example, An A-control field orother indicator in a header of a data frame 418 may inform the non-APMLD 120 to deactivate the auxiliary link 134. The non-AP MLD 120 maydeactivate 419 the non-AP MLD 120 at the conclusion of a next packetexchange or acknowledgment.

Notice that the timing for a first communication 416 on the auxiliarylink 134 may be delayed to accommodate a warm up time for the associatedSTA interface of non-AP MLD 120 to activate 413 the auxiliary link. Insome implementations, the non-AP MLD 120 may send a configuration valueto indicate the warm up time in a configuration or negotiation message(such as when the multi-link association is first established).Alternatively, the ACK from the non-AP MLD 120 may indicate that thenon-AP MLD 120 is ready to receive communication on the auxiliary link134. Alternatively, or additionally, the delay before the firstcommunication 416 may be in the form of initial padding data in thefirst communication 416 before data intended for the non-AP MLD 120.

FIG. 4B shows a pictorial diagram 402 of example signaling to activate alink of a multi-link association using a broadcast addressed frame. Inthis example, the non-AP MLD 120 may periodically wake up an auxiliarylink 134 to receive broadcast frames (such as Beacon Frames 410) anddetermine whether the Beacon Frame 410 includes an indicator to activatethe auxiliary link 134. For example, the broadcast frame may indicatetraffic associated with a TID that is mapped to the auxiliary link 134.Initially, the non-AP MLD 120 may have the auxiliary link 134 in adeactivated state 411, such that the STA interface for the auxiliarylink 134 is in a power saving mode or doze state. Upon detecting theindicator in a Beacon Frame 410 to activate the auxiliary link 134, thenon-AP MLD 120 may activate 413 the auxiliary link 134. Data 415 may besent via both the anchor link 132 and the auxiliary link 134. In someimplementations, the non-AP MLD 120 may send a message to the AP MLD 110to indicate which links (such as one or both of the anchor link 132 andthe auxiliary link 134) that non-AP MLD 120 will be available to receivethe data 415. After the data 415 has been transmitted, at some point thenon-AP MLD 120 may deactivate 419 the auxiliary link 134 to conservepower.

FIG. 4C shows a pictorial diagram 403 of example signaling regardingtarget wake time (TWT) coordination in multi-link communication. Thenon-AP MLD 120 may negotiate TWT schedules during which the auxiliarylinks 134 are activated. The TWT schedule may define TWT service periods(TWT SPs) 433 for communication via the anchor link 132 and theauxiliary link 134. The schedules for TWTs of the anchor link 132 andthe auxiliary link 134 may be aligned (as shown in FIG. 4C) or may notbe aligned. During the TWTs, the AP MLD 110 may signal whether theauxiliary link 134 should remain activated or should be deactivated.

FIG. 4D shows a pictorial diagram 404 of example signaling regardingtiming to activate a link of a multi-link association. The example ofFIG. 4D shows explicit frames 441 and 442 on the anchor link 132 toindicate that the auxiliary link 134 should be activated 413 anddeactivated 419, respectively. Thus, the AP MLD 110 may explicitlymanage the activation and deactivation of the auxiliary link 134 usingmanagement or control frames.

FIG. 4E shows a pictorial diagram 405 of example signaling to activate alink of a multi-link association using a preamble indicator. One or morebits in the preamble of a PPDU from the AP MLD 110 may indicate aninstruction to for the non-AP MLD 120 to activate 413 the auxiliary link134. In some implementations, each PPDU may include signaling toinstruct the non-AP MLD 120 to activate or deactivate the auxiliary link134. In some implementations, the signaling may be a traffic indicatorand the non-AP MLD 120 may infer that the auxiliary link 134 should beactivated to receive the traffic. In the example of FIG. 4E, a firstdata frame includes a preamble 451 causing the non-AP MLD 120 toactivate 413 the auxiliary link 134. Data may be transmitted via theanchor link 132 and the auxiliary link 134. In a subsequent PPDU, the APMLD 110 may include a preamble 453 that causes the non-AP MLD 120 todeactivate 419 the auxiliary link 134. For example, when sending thelast packet of buffered data, the AP MLD 110 may include thedeactivation indicator in the preamble 453 of that last packet.

FIG. 5A shows a pictorial diagram 501 of example signaling for downlinkcommunication in a multi-link association with spatial multiplexing. Inspatial multiplexing, the AP MLD 110 and the non-AP MLD 120 may usemultiple-input-multiple-output (MIMO) to establish SS spatial streams.The quantity of spatial streams may be based on the number of transmitantennas Ntx and the number of receive antennas Nrx. While spatialmultiplexing may support greater throughput, the use of spatialmultiplexing utilizes more processing capability (and thus more power)at the MLDs. The non-AP MLD 120 may be powered by a battery andtherefore it may be desirable to limit power consumption when possible.FIG. 5A shows an example of power saving in which single streamprocessing is used for times when little or no data is beingcommunicated and MIMO can be enabled when more data is beingcommunicated.

Initially, the auxiliary link 134 may be in a deactivated state 511.Furthermore, the AP MLD 110 and the non-AP MLD 120 may use single stream(non-MIMO) communication for maintaining the anchor link 132 until thereis data to communicate. Because the example of FIG. 5A is based ondownlink (DL) communication from the AP MLD 110 to the non-AP MLD 120,the AP MLD 110 may initiate the DL communication by transmitting arequest to send (RTS) 512 message to alert the non-AP MLD 120 of thepending DL communication. The non-AP MLD 120 may respond with a clear tosend (CTS) 513 message. Both the RTS message 512 and the CTS message 513are relatively simple and short communications, so MIMO is not neededfor those communications. However, once the non-AP MLD 120 receives theRTS message 512 and either after sending or currently with sending theCTS message 513, the non-AP MLD 120 may activate 514 the auxiliary link134. Furthermore, the non-AP MLD 120 may change the configuration of itsRF chain to utilize MIMO communication for SS spatial streams. There maybe a delay 523 (such as a short interframe space, SIFS, duration) beforethe AP MLD 110 transmits the MIMO communication via the auxiliary link134. This delay 523 may be based on an amount of time for the non-AP MLD120 to activate the auxiliary link 134 as well as the amount of time forthe non-AP MLD 120 to configure its radio interface for MIMOcommunication 520. The AP MLD 110 may transmit spatial multiplexed data521 and 521 via the anchor link 132 and the auxiliary link 134,respectively. In some implementations, the non-AP MLD 120 may respondwith block acknowledgements (BA 525 and 526) on the respective links 132and 134. At some point (such as following a time period after thecompletion of the last data transmission), the non-AP MLD 120 maydeactivate the auxiliary link 134 and revert to non-MIMO operation toconserve power.

As another example, the non-AP MLD 120 may activate multiple RX chainswhen it receives start of a frame exchange. The frame exchange sequencestarts with individually addressed frame sent to the non-AP MLD 120. Theframe exchange sequence may require an immediate response (RTS/CTS inthe example). The individually addressed frame may be sent with onespatial stream (for example).

Thereafter, the frame exchange sequence with the non-AP MLD 120 cancontinue with frames that are sent with multiple spatial streams in link1 (anchor link 132). In some implementations, a separation of 1 SS TXto >1 SS RX frames can be SIFS. The frames that are sent with multiplespatial streams may be in link 2 (auxiliary link 134). Activation of theauxiliary link 134 may occur at or after the time of activating multipleSS in link 1.

Termination of exchange sequence in each link can be independent &identified by reception of frame addressed to another non-AP MLD (notshown), or generated by another non-AP MLD (not shown), a pointcoordination function (PCF) interframe space (PIFS) or the like, afterwhich the non-AP MLD 120 may switch RX SS to 1 for the anchor link 132and the auxiliary link 134. And, eventually, the non-AP MLD 120 maydeactivate the auxiliary link 134.

FIG. 5B shows a pictorial diagram 502 of example signaling for uplinkcommunication in a multi-link association with spatial multiplexing. Anon-AP MLD 120 may send a power save poll (PS-Poll, or PSP 517), aquality of service null (QoS Null), an RTS, or other message via theanchor link 132 to initiate an uplink communication. The AP MLD 110 mayrespond with an acknowledgement 518 or other message to indicate thatthe anchor link 132 and the auxiliary link 134 are available formulti-link UL communication. Based on the ACK message 518, the non-APMLD 120 may activate 514 the auxiliary link 134 and transmit UL data 521and 522 via the anchor link 132 and the auxiliary link 134,respectively. As described in FIG. 5A, there may be a delay 523 beforetransmission of the data 522 on the auxiliary link 134 to provide timefor activation 514 of the auxiliary link 134 and the SS for UL MIMO 520.Similar to FIG. 5A, the non-AP MLD 120 may deactivate 529 the auxiliarylink 134 after a time period following the uplink MIMO communication.

FIG. 5C shows a pictorial diagram 503 of an enhanced multi-link singleradio (eMLSR) technique for an MLD that has a single radio with multipleavailable antennas. For example, the non-AP MLD 120 may have 2 or moreantennas for use with MIMO but only a single radio. The non-AP MLD 120may use an antenna to concurrently sense for basic signals on both theanchor link 132 and the auxiliary link 134. For example, the non-AP MLD120 may use a 1×1 (single antenna) mode to detecting energy on the links132 and 134 when the non-AP MLD 120 is idle. Upon detecting an RTS formthe AP MLD 110 or sending an RTS 532, the non-AP MLD 120 may switch from1×1 on both links to a 2×2 mode on just one of the links. In the examplein FIG. 5C, the non-AP MLD 120 initiates UL MIMO communication bysending an RTS 532 and receiving a CTS 533 via the anchor link 132.These messages may be sent using single antenna (SS=1) communication.When sending the data 542 to the AP MLD 110 (or receiving data from theAP MLD 110), the non-AP MLD 120 may deactivate one of the links so thatmultiple antennas may be used with the single radio on just one of thelinks. In the example of FIG. 5C, the non-AP MLD 120 deactivates 539 theauxiliary link 134 and uses the antenna that was previously configuredin 1×1 mode for that link with the antenna that was previouslyconfigured in 1×1 mode for the anchor link 132 to form a 2×2 mode usingboth antennas on the anchor link 132. The non-AP MLD 120 may send thedata 542 using the 2×2 mode. During UL MIMO communication 520, becausethe non-AP MLD 120 in this example is a single-radio device, it cannottransmit or receive via the auxiliary link 134. However, having theability to configure a single radio device as a non-AP MLD 120 may beadvantageous for the seamless establishment and multi-link associationbetween the single-radio non-AP MLD 120 and the AP MLD 110. Even thoughthe non-AP MLD 120 may only use one of the links at a time, having bothlinks configured may provide flexibility to adjust which frequency bandor spatial stream configuration to use based on type or amount oftraffic.

FIG. 6A is a diagram illustrating an example physical layer convergenceprocedure (PLCP) protocol data unit (PPDU) frame 600. As shown in FIG.6A, the PPDU frame 600 includes a physical layer (PHY) header 615 andone or more PLCP service data units (such as PSDU 680). Each of thePSDUs may be addressed to a receiver (individually addressed), a groupof receivers (group addressed) or to all receivers (broadcastaddressed). Similarly, it may be sent by a transmitter, a group oftransmitters, or all transmitters, or a combination of both. The PDSU680 includes zero or more MPDUs. In FIG. 6A, the PSDU 680 includes oneMPDU. Each MPDU may include one or more of the following fields: a MACheader field 650, a payload/data field 660, and a frame check sequence(FCS) field 670. The PSDU 680 also may be referred to as a payloadportion 680 of the PPDU frame 600. The PHY header 615may be used toacquire an incoming signal (such as an OFDMA signal), to train andsynchronize a demodulator, and may aid in demodulation and delivery ofthe payload portion 680.

In some implementations, the MPDUs may be included in the PSDU 680 aspart of an aggregated MPDU (A-MPDU).

FIG. 6B shows a diagram of an example aggregated media access control(MAC) protocol data unit (A-MPDU) frame. The PHY header 615 is omittedfor brevity. Following the PHY header, a series of MPDU may be organizedas A-MPDU subframes. Each A-MPDU subframe (such as A-MPDU subframe 640)may include an MPDU delimiter 690, an MPDU 696, and padding 698. TheMPDU 692 may have a similar structure as described with regard to FIG.6A. For example, the MPDU 692 may include one or more of the followingfields: a MAC header field 650, a payload/data field 660, and a framecheck sequence (FCS) field 670.

FIG. 7 shows a flowchart illustrating an example process 700 formanaging a multi-link association. In some implementations, the process700 may be performed by a wireless communication device such as an APMLD or non-AP MLD. In block 710, a wireless communication device mayestablish a multi-link association between an AP MLD and a non-AP MLD.The multi-link association may include a first link between a first STAinterface of the non-AP MLD and a first BSS of the AP MLD and mayfurther include a second link between a second STA interface of thenon-AP MLD and a second BSS of the AP MLD. In block 720, the wirelesscommunication device may send or receive signaling, via the first link,to activate or deactivate the second link

FIG. 8 shows a diagram of an example medium access control (MAC) framewith an Aggregated Control (A-Control) field. In some implementations,the MAC frame 800 may include a media access control protocol data unit(MPDU) frame. In some implementations, the MAC frame 800 may correspondto the payload portion 680, as previously described in FIG. 6 . Asshown, the MAC frame 800 includes one or more of several differentfields: a frame control (FC) field 810, a duration/identification field825, a receiver address (A1) field 870, a transmitter address (A2) field875, a destination address (A3) field 840, a sequence control (SC) field845, a fourth address (A4) field 850, a quality of service (QoS) control(QC) field 855, a high throughput (HT)/very high throughput (VHT)control field 860, a frame body 868, and a frame check sequence (FCS)field 670. Some or all of the fields 810-865 may make up the MAC header650 of FIG. 6 . In some implementations, a protocol version field of theframe control field 810 of the MAC frame 800 can be 0, or 1 or greaterthan 1.

The A-Control field 862 may be included in a High Throughput (HT)Control field 860. Alternatively, the A-Control field may be includedafter the HT Control field or immediately after the CCMP Header (in thislatter case the information can be encrypted). Counter Mode Cipher BlockChaining Message Authentication Code Protocol (Counter Mode CBC-MACProtocol) or CCM mode Protocol (CCMP) is an encryption protocol designedfor WLAN devices that implements the standards of the IEEE 802.11i. Inthe examples of this disclosure, the A-Control field is included in anHT Control field 860. However, other locations for the A-Control field862 may be possible.

In accordance with this disclosure, an A-Control field may be a DynamicA-Control field (also referred to as an Enhanced A-Control field). Forexample, the A-Control field may be a variable-length field in an MPDU.A first portion of the A-Control field may indicate the length of theA-Control field. For example, the first portion may be formatted as acontrol header (sometimes also referred to as a control delimiter ordelimiter). The control header may have a format mimicking a controlparameter within the A-Control field. For example, the control headermay be structured similar to the control parameters and may have aspecific value (such as a series of binary ones) for the Control ID. Thespecific value indicates that the control header is a type of controlparameter that contains the length of the A-Control field. The controlheader may be included as the first control parameter of the A-Controlfield to indicate the length of the A-Control field. Alternatively, thecontrol header may be located at any location within the A-Control fieldand can indicate either the length of the full A-Control field or of theremaining portion (following the control header) of the A-Control field.Thus, the A-Control field may be variable-length to support signalingmultiple types of control information. For example, the length of theA-Control field may vary between 4 bytes (baseline) and 64 bytes(maximum). The length of the A-Control field may be indicated by alength value and the length value may represent groups of octets (suchas 1, 2, or 4 octets for each integer length value).

In some implementations, the specific control ID may be all ones (inwhich case, assuming the control ID is 4 bits long, the all ones binaryvalue would have a decimal value of 15. Although the all ones example isused in this disclosure, the specific value may be any value that issupported by the recipient and that is not used as a control ID forother purposes. Following the specific control ID, the controlinformation in the control header may indicate the length value aseither a zero-length value, a non-zero value, or an all-ones lengthvalue. For example, a control parameter referred to as “ONES-NZL” (allones for Control ID followed by a non-zero length value less than amaximum) may indicate that the A-Control field is a variable-lengthA-Control field having a length indicated by the non-zero length value.In some implementations, a control parameter referred to as a “ONES-EOF”(all ones for Control ID followed by all ones for the value) mayindicate an end of the A-Control field. A control parameter referred toas “ONES-ZL” (all ones for Control ID followed by a zero-length value)may be used as a delimiter between different subsets of the controlparameters included in the A-Control field.

For example, the most significant bit (MSB) of the traffic indicator(TID) field of the QoS Control field are currently reserved and set to0. In some implementations, the setting of the MSB of the TID field to 1may be used to indicate that the control information being provided bythe A-Control field that follows in the same MPDU is relative to theauxiliary link (different from the anchor link on which the MPDU isbeing sent). The anchor link is the link where the frame is being sent,and auxiliary link is the link where the frame is not being sent. Usingjust one bit (such as the MSB of the TID field), the transmitting devicemay distinguish up to two links. The transmitting device may includeMPDUs with different values of the MSB bit of the TID of the QoS Controlif it wants to signal different control information for the twodifferent links. For example, a first MPDU (with the MSB of the TID setto 0) may include an A-Control field with aggregated control informationfor the anchor link. A second MPDU (with the MSB of the TID set to 1)may include an A-Control field with control information for theauxiliary link.

In some implementations, the ONES-NZL may be the first control parameterin the A-Control field and may indicate an overall length of the DynamicA-Control (with control parameters for multiple links). After a firstsubset of control parameters (such as for the anchor link), a delimitermay indicate whether control parameters for one or more auxiliary linksis included. If no control information is available for a link, then aONES-ZL may be used. Alternatively, the ONES-ZL may precede the controlinformation for each of the auxiliary links. In some implementations, aONES-EOF or Padding can be used to populate a remaining portion of theDynamic A-Control field.

FIG. 8 also shows an A-Control field 862 as a series of controlparameters (Control 1, Control 2, etc.). Each control parameter (such asa first control parameter 872) may be identified by a control identifier(ID) 874 that serves as a header the control parameter in a sequence ofcontrol parameters. Following the Control ID 874, the controlinformation 878 may have a different length depending on the control ID874 value.

In legacy systems, the length of the A-Control field was limited to 30bits. The container (such as the HT Control field) of the A-Controlfield may have a total length of 32 bits, which includes 2 leadingindicators, and 30 bits for control parameters. However, the limitedsize of the A-Control field constrains the quantity of controlparameters that may be included. For example, the A-Control field mayhave been constrained to one or two control parameters depending onwhich control parameters were included.

In accordance with this disclosure, the A-Control field may have alonger length and may be variable in size to accommodate more controlparameters. In the descriptions below, the length of the A-Control fieldmay be described in a control header of the A-Control field. The controlheader may indicate a length of the container (such as the HT-Controlfield) of the A-Control field, or of the A-Control field itself. Becausethe length of the A-Control field and the HT-Control field are related,in this disclosure, references to the length of the A-Control field maybe used interchangeably with reference to the length of the container(such as the HT-Control field) carrying the A-Control field. To indicatethe length of the A-Control field, one of the control parameters may berepurposed to include the length value as control information. Forexample, a specific value for the control ID that is currently reserved,at least in part, may be used to indicate the length of the A-controlfield or to provide delimiters for multiple control parameters. In theimplementations below, we describe the case where the Control ID valueis equal to 15. Although the examples in this disclosure use the ONESvalue (control ID 15), it is also possible to use one of the reservedvalues (control ID 7 to 14) to indicate the length of the A-ControlField or the presence of another field following the Control ID fieldthat indicates the length of the A-Control field. In someimplementations, the length may indicate the length of the remainingportion of the A-Control field, or of a sub-portion of the A-Controlfield as described in more detail in some of the examples below.

FIGS. 9A and 9B show various options of an A-Control field that includescontrol parameters for one or more links of a multi-link association. InFIG. 9A, each link has separate control parameters. A first portion ofthe A-Control field is the ONES-NZL 910 that indicates the overalllength of the A-Control field. The ONES-NZL 910 field may be followed bycontrol parameters 920 for a first link 1 (such as control parameters A1and A2). Then delimiters (the ONES-ZL field 930) may signal that thecontrol parameters for the first link are complete and the next controlparameters are for the next link 2. The control parameters 940 for link2 (control parameters B1 and B2) may follow the ONES-ZL field 930).

As shown in FIG. 9B, if one of the links (such as link 2) does not havecontrol parameters that need to be sent, the ONES-ZL field 930 may befollowed by another ONES-ZL field 990 to begin the next link (link 3)section of control parameters 960 (with control parameters C1 and C2).

FIG. 9C shows an example of explicit indicators for multi-linkaggregated control parameters. For example, each control parameter mayhave an explicit indicator (such as a link identifier, Link ID 979)included in a control parameter 970. The Link ID 979 may be includedbetween the control ID 974 and the control information 978. In someimplementations, the Link ID 979 may be included in the control IDs thatare used as delimiters (such as the ONES-NZL and ONES-ZL examples inthis disclosure).

FIG. 9D shows another example of an A-Control field with controlparameters for one or more links of a multi-link association. In FIG.9D, each link has separate control parameters. A first portion of theA-Control field is the ONES-NZL 910 that indicates the overall length ofthe A-Control field. The ONES-NZL 910 field may be followed by controlparameters 920 for a first link 1 (such as control parameters A1 andA2). Then another delimiter (the ONES-NZL field 931) may signal that thecontrol parameters for the first link are complete and the next controlparameters are for the next link 2. The control parameters 940 for link2 (control parameters B1 and B2) may follow the ONES-NZL field 931). AONES-EOF field 980 may be used to signal the end of the A-Control fieldthat has control parameters for multiple links. For example, theONES-EOF may include an all-ONES (control ID=15) followed by an all-oneslength value.

FIG. 9E shows an example of an A-Control field with control parametersfor multiple links without using delimiters. For example, if eachcontrol parameters include an explicit link ID (as shown in FIG. 6 ),then the delimiters may be omitted. Alternatively, the order andoccurrence of control parameters may implicitly indicate that they arefor different links. For example, an A-Control field for a single linkwould not include more than one control parameter with the same ControlID. Therefore, if the same control ID is present in the A-Control field,the second occurrence of the control ID may implicitly signal the changeto the next link. Using the example in FIG. 9E, a first set of controlparameters 920 is related to a first link 1 and a second set of controlparameters 940 may be related to a second link 2. The control parameterA1 may have the same control ID as the control parameter B1. When therecipient processes the A-Control field and detects control parameter B1having the same control ID as control parameter A1, the recipient maydetermine that the control parameter B1 may be related to the secondlink.

As described herein, there may be various ways to include controlparameters for multiple links. These techniques, or variations thereof,may be useful to activate and deactivate one or more links of amulti-link association. For example, an OM control parameter may setparticular bits (such as the UL MU Disable or the UL MU Data Disablebits) to a first value (such as 1) to indicate deactivation of thatlink. In some implementations, a new control ID (such as one of thereserved values) may be defined to contain information related to linkdeactivation. For example, the control parameter may include a targetswitch time of the state (activated or deactivated) change. In someimplementations, the activation and deactivation may be used to force arecipient to move from a first link to a second link. For example, afirst link may be indicated to be deactivation at a target switch timewhile a second link may be indicated to be activation at the targetswitch time.

In some implementations, the time value may be relative based on a startor end time of the frame that carries the control parameters. Forexample, the time value may be a time offset relative to the frame. Insome implementations, the timing information may include a timestamp orother time that is based on a synchronized time. A timingsynchronization function (TSF) timer may be maintained in both thesending device and the receiving device. The timing information for alink activation or link deactivation may be a full or partial timestampbased on the TSF timer. In some implementations, the sending device andreceiving device may maintain separate TSF timers for the first link andthe second link. The timing information for activation or deactivationmay be specific to the TSF timer for a particular link.

FIG. 10 depicts an example message flow diagram associated withmulti-link communication. The example message flow 1000 shows an AP MLD110 and a non-AP MLD 120. The AP MLD 110 and the non-AP MLD 120 mayestablish a multi-link association at 1012. For example, the AP MLD 110and the non-AP MLD 120 may exchange configuration messages to verifythey both support the multi-link communication features (such asmulti-link association and signaling) of this disclosure. The multi-linkassociation may include an anchor link and at least one auxiliary linkthat are both configured during the multi-link association establishmentprocess.

At process 1010, the AP MLD 110 may determine to activate or deactivatethe auxiliary link. The first frame 1022 may include signaling regardingactivation or deactivation of the auxiliary link. In the example of FIG.10 , the first frame 1022 includes an indicator to signal activation ofthe auxiliary link. At 1032, the non-AP MLD 120 may activate theauxiliary link. In some implementations, the non-AP MLD 120 may send anacknowledgment message to indicate that the auxiliary link has beenactivated. In some implementations, the acknowledgment message 1034 mayinclude an indicator that indicates whether the non-AP MLD 120 properlyprocessed the first frame 1022. At process 1042, the AP MLD 110 mayprocess the acknowledgment message 1034 and determine whether theauxiliary link has been activated. At 1052, the AP MLD 110 maycommunicate with the non-AP MLD 120 via the anchor link and theauxiliary link concurrently.

FIG. 11 shows a block diagram of an example wireless communicationdevice 1100. The wireless communication device 1100 can be an example ofan AP MLD 110 or a non-AP MLD 120, such as those described herein. Insome implementations, the wireless communication device 1100 can be anexample of a device for use in a STA such as one of the STAs 104, 144described herein. In some implementations, the wireless communicationdevice 1100 can be an example of a device for use in an AP such as theAP 102 described herein. The wireless communication device 1100 iscapable of transmitting (or outputting for transmission) and receivingwireless communications (for example, in the form of wireless packets).For example, the wireless communication device can be configured totransmit and receive packets in the form of physical layer convergenceprotocol (PLCP) protocol data units (PPDUs) and Media Access Control(MAC) protocol data units (MPDUs) conforming to an IEEE 802.11 standard,such as that defined by the IEEE 802.11-2016 specification or amendmentsthereof including, but not limited to, 802.11ah, 802.11ad, 802.11ay,802.11ax, 802.11az, 802.11ba, 802.11be and further such amendments.

The wireless communication device 1100 can be, or can include, a chip,system on chip (SoC), chipset, package or device that includes one ormore modems 1102, for example, a Wi-Fi (IEEE 802.11 compliant) modem. Insome implementations, the one or more modems 1102 (collectively “themodem 1102”) additionally include a WWAN modem (for example, a 3GPP 4GLTE or 5G compliant modem). In some implementations, the wirelesscommunication device 1100 also includes one or more radios (collectively“the radio 1104”). In some implementations, the wireless communicationdevice 1100 further includes one or more processors, processing blocksor processing elements (collectively “the processor 1106”) and one ormore memory blocks or elements (collectively “the memory 1108”).

The modem 1102 can include an intelligent hardware block or device suchas, for example, an application-specific integrated circuit (ASIC) amongother possibilities. The modem 1102 is generally configured to implementa PHY layer. For example, the modem 1102 is configured to modulatepackets and to output the modulated packets to the radio 1104 fortransmission over the wireless medium. The modem 1102 is similarlyconfigured to obtain modulated packets received by the radio 1104 and todemodulate the packets to provide demodulated packets. In addition to amodulator and a demodulator, the modem 1102 may further include digitalsignal processing (DSP) circuitry, automatic gain control (AGC), acoder, a decoder, a multiplexer and a demultiplexer. For example, whilein a transmission mode, data obtained from the processor 1106 isprovided to a coder, which encodes the data to provide encoded bits. Theencoded bits are mapped to points in a modulation constellation (using aselected MCS) to provide modulated symbols. The modulated symbols may bemapped to a number N_(SS) of spatial streams or a number N_(STS) ofspace-time streams. The modulated symbols in the respective spatial orspace-time streams may be multiplexed, transformed via an inverse fastFourier transform (IFFT) block, and subsequently provided to the DSPcircuitry for Tx windowing and filtering. The digital signals may beprovided to a digital-to-analog converter (DAC). The resultant analogsignals may be provided to a frequency upconverter, and ultimately, theradio 1104. In implementations involving beamforming, the modulatedsymbols in the respective spatial streams are precoded via a steeringmatrix prior to their provision to the IFFT block.

While in a reception mode, digital signals received from the radio 1104are provided to the DSP circuitry, which is configured to acquire areceived signal, for example, by detecting the presence of the signaland estimating the initial timing and frequency offsets. The DSPcircuitry is further configured to digitally condition the digitalsignals, for example, using channel (narrowband) filtering, analogimpairment conditioning (such as correcting for UQ imbalance), andapplying digital gain to ultimately obtain a narrowband signal. Theoutput of the DSP circuitry may be fed to the AGC, which is configuredto use information extracted from the digital signals, for example, inone or more received training fields, to determine an appropriate gain.The output of the DSP circuitry also is coupled with the demodulator,which is configured to extract modulated symbols from the signal and,for example, compute the logarithm likelihood ratios (LLRs) for each bitposition of each subcarrier in each spatial stream. The demodulator iscoupled with the decoder, which may be configured to process the LLRs toprovide decoded bits. The decoded bits from all of the spatial streamsare fed to the demultiplexer for demultiplexing. The demultiplexed bitsmay be descrambled and provided to the MAC layer (the processor 1106)for processing, evaluation or interpretation.

The radio 1104 generally includes at least one radio frequency (RF)transmitter (or “transmitter chain”) and at least one RF receiver (or“receiver chain”), which may be combined into one or more transceivers.For example, the RF transmitters and receivers may include various DSPcircuitry including at least one power amplifier (PA) and at least onelow-noise amplifier (LNA), respectively. The RF transmitters andreceivers may in turn be coupled to one or more antennas. For example,in some implementations, the wireless communication device 1100 caninclude, or be coupled with, multiple transmit antennas (each with acorresponding transmit chain) and multiple receive antennas (each with acorresponding receive chain). The symbols output from the modem 1102 areprovided to the radio 1104, which transmits the symbols via the coupledantennas. Similarly, symbols received via the antennas are obtained bythe radio 1104, which provides the symbols to the modem 1102.

The processor 1106 can include an intelligent hardware block or devicesuch as, for example, a processing core, a processing block, a centralprocessing unit (CPU), a microprocessor, a microcontroller, a digitalsignal processor (DSP), an application-specific integrated circuit(ASIC), a programmable logic device (PLD) such as a field programmablegate array (FPGA), discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. The processor 1106 processes information receivedthrough the radio 1104 and the modem 1102, and processes information tobe output through the modem 1102 and the radio 1104 for transmissionthrough the wireless medium. For example, the processor 1106 mayimplement a control plane and MAC layer configured to perform variousoperations related to the generation and transmission of MPDUs, framesor packets. The MAC layer is configured to perform or facilitate thecoding and decoding of frames, spatial multiplexing, space-time blockcoding (STBC), beamforming, and OFDMA resource allocation, among otheroperations or techniques. In some implementations, the processor 1106may generally control the modem 1102 to cause the modem to performvarious operations described above.

The memory 1108 can include tangible storage media such as random-accessmemory (RAM) or read-only memory (ROM), or combinations thereof. Thememory 1108 also can store non-transitory processor- orcomputer-executable software (SW) code containing instructions that,when executed by the processor 1106, cause the processor to performvarious operations described herein for wireless communication,including the generation, transmission, reception and interpretation ofMPDUs, frames or packets. For example, various functions of componentsdisclosed herein, or various blocks or steps of a method, operation,process or algorithm disclosed herein, can be implemented as one or moremodules of one or more computer programs.

In some implementations, the wireless communication device 1100 mayinclude a multi-link communication control unit (not shown). Themulti-link communication control unit may be similar to the multi-linkcommunication control unit 112 or the multi-link communication controlunit 122 described with reference to FIG. 2B and may implement any ofthe techniques described herein. In some implementations, the multi-linkcommunication control unit may be implemented by a processor 1106 and amemory 1108. The memory 1108 can include computer instructionsexecutable by the processor 1106 to implement the functionality ofmulti-link communication control unit. Any of these functionalities maybe partially (or entirely) implemented in hardware or on the processor1106.

FIG. 12A shows a block diagram of an example AP 1202. The AP 1202 can bean example of an AP MLD 110, such as those described herein. The AP 1202can be an example implementation of the AP 102 described herein. The AP1202 includes a wireless communication device (WCD) 1210. For example,the wireless communication device 1210 may be an example implementationof the wireless communication device 1100 described with reference toFIG. 11 . The AP 1202 also includes multiple antennas 1220 coupled withthe wireless communication device 1210 to transmit and receive wirelesscommunications. In some implementations, the AP 1202 additionallyincludes an application processor 1230 coupled with the wirelesscommunication device 1210, and a memory 1240 coupled with theapplication processor 1230. The AP 1202 further includes at least oneexternal network interface 1250 that enables the AP 1202 to communicatewith a core network or backhaul network to gain access to externalnetworks including the Internet. For example, the external networkinterface 1250 may include one or both of a wired (for example,Ethernet) network interface and a wireless network interface (such as aWWAN interface). Ones of the aforementioned components can communicatewith other ones of the components directly or indirectly, over at leastone bus. The AP 1202 further includes a housing that encompasses thewireless communication device 1210, the application processor 1230, thememory 1240, and at least portions of the antennas 1220 and externalnetwork interface 1250.

FIG. 12B shows a block diagram of an example STA 1204. The STA 1204 canbe an example of a non-AP MLD 120, such as those described herein. TheSTA 1204 can be an example implementation of the STA 104, 144 describedherein. The STA 1204 includes a wireless communication device 1215. Forexample, the wireless communication device 1215 may be an exampleimplementation of the wireless communication device 1100 described withreference to FIG. 11 . The STA 1204 also includes one or more antennas1225 coupled with the wireless communication device 1215 to transmit andreceive wireless communications. The STA 1204 additionally includes anapplication processor 1235 coupled with the wireless communicationdevice 1215, and a memory 1245 coupled with the application processor1235. In some implementations, the STA 1204 further includes a userinterface (UI) 1255 (such as a touchscreen or keypad) and a display1265, which may be integrated with the UI 1255 to form a touchscreendisplay. In some implementations, the STA 1204 may further include oneor more sensors 1275 such as, for example, one or more inertial sensors,accelerometers, temperature sensors, pressure sensors, or altitudesensors. Ones of the aforementioned components can communicate withother ones of the components directly or indirectly, over at least onebus. The STA 1204 further includes a housing that encompasses thewireless communication device 1215, the application processor 1235, thememory 1245, and at least portions of the antennas 1225, UI 1255, anddisplay 1265.

FIG. 13 depicts a conceptual diagram of an example frame for multi-linkcommunication. For example, the example frame 1300 may be sent from anAP to a wireless device or from a wireless device to an AP. In someimplementations, the example frame 1300 may include or be included in aconfiguration message. The example frame 1300 may be defined by the IEEE802.11 specification. In some other implementations, the example frame1300 may be a new frame format created to facilitate multi-linkcommunication. One example of the example frame 1300 may include anenhanced beacon frame that may be used by IEEE 802.11 (similar to thebeacon frames defined for IEEE 802.11ax). Another example of an exampleframe 1300 may be a synchronization frame or other short frame that maybe defined for other technologies (or next generation of IEEE 802.11,beyond 802.11ax).

The example frame 1300 may include a header 1324 and a payload 1310. Insome implementations, the header 1324 may include source addresses (suchas the network address of the sending AP), the length of data frame, orother frame control information. The payload 1310 may be used to conveythe multi-link communication capability or configuration information.The multi-link communication capability or configuration information maybe organized or formatted in a variety of ways.

In some implementations, the example frame 1300 may include a preamble1322. The preamble 1322 may be used, for example, when the transmissionis non-triggered or non-scheduled. In some implementations, the preamblemay be omitted for triggered or scheduled transmissions. When thepreamble is present, the preamble 1322 may include one or more bits toestablish synchronization. The example management frame 1300 may includean optional frame check sequence (FSC) 1326. The payload 1310 may beorganized with a message format and may include information elements1332, 1336, and 1338.

Several examples of information elements 1360 are illustrated in FIG. 13. The information elements 1360 may include multi-link communicationcapability information 1362, a warm up time period 1364, or signaling1372.

FIG. 14 shows a flowchart illustrating an example process 1400 forconnecting to services. In some implementations, the process 1400 may beperformed by a wireless communication device such as an AP MLD or non-APMLD.

In block 1410, the non-AP MLD may establish a multi-link associationwith an AP MLD. The multi-link association may include a first linkbetween a first STA interface of the non-AP MLD and a first BSS of theAP MLD and may further include a second link between a second STAinterface of the non-AP MLD and a second BSS of the AP MLD.

In block 1420, the non-AP MLD may determine that the second link can bedeactivated based, at least in part, on an amount of traffic for thesecond link being below a threshold amount.

In block 1430, the non-AP MLD may deactivate the second link by causingthe second STA interface to enter a doze state.

FIG. 15 shows a block diagram of an example wireless communicationdevice 1500 for use in wireless communication. In some implementations,the wireless communication device 1500 can be an example of an AP MLD110 or a non-AP MLD 120, such as those described herein. In someimplementations, the wireless communication device 1500 can be anexample of the STA 104, 144, 1204 or the wireless communication devices1100, 1215 described herein. In some implementations, the wirelesscommunication device 1500 can be an example of the AP 102, 1202 orwireless communication devices 1100, 1210. In some implementations, thewireless communication device 1500 is configured to perform one or moreof the processes described herein. The wireless communication device1500 includes a multi-link association module 1502, a protocolimplementation module 1506, and a communication link module 1510.Portions of one or more of the modules 1502, 1506 and 1510 may beimplemented at least in part in hardware or firmware. In someimplementations, at least some of the modules 1502, 1506 and 1510 areimplemented at least in part as software stored in a memory (such as thememory 1108, 1240, or 1245). For example, portions of one or more of themodules 1502, 1506 and 1510 can be implemented as non-transitoryinstructions (or “code”) executable by at least one processor (such asthe processor 1106) to perform the functions or operations of therespective module.

The multi-link association module 1502 may manage the establish amulti-link association with another MLD. For example, the multi-linkassociation module 1502 may establish a multi-link association with anAP MLD. The protocol implementation module 1506 may implement amulti-link association protocol between the wireless device the otherMLD. For example, the protocol implementation module 1506 may beconfigured to interpret any of the signaling described herein. Thecommunication link module 1510 may manage the activation or deactivationof auxiliary links of a multi-link association.

FIGS. 1-15 and the operations described herein are examples meant to aidin understanding example implementations and should not be used to limitthe potential implementations or limit the scope of the claims. Someimplementations may perform additional operations, fewer operations,operations in parallel or in a different order, and some operationsdifferently.

As used herein, a phrase referring to “at least one of” or “one or moreof” a list of items refers to any combination of those items, includingsingle members. For example, “at least one of: a, b, or c” is intendedto cover the possibilities of: a only, b only, c only, a combination ofa and b, a combination of a and c, a combination of b and c, and acombination of a and b and c.

The various illustrative components, logic, logical blocks, modules,circuits, operations and algorithm processes described in connectionwith the implementations disclosed herein may be implemented aselectronic hardware, firmware, software, or combinations of hardware,firmware or software, including the structures disclosed in thisspecification and the structural equivalents thereof. Theinterchangeability of hardware, firmware and software has been describedgenerally, in terms of functionality, and illustrated in the variousillustrative components, blocks, modules, circuits and processesdescribed above. Whether such functionality is implemented in hardware,firmware or software depends upon the particular application and designconstraints imposed on the overall system.

The hardware and data processing apparatus used to implement the variousillustrative components, logics, logical blocks, modules and circuitsdescribed in connection with the aspects disclosed herein may beimplemented or performed with a general purpose single- or multi-chipprocessor, a digital signal processor (DSP), an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA) orother programmable logic device (PLD), discrete gate or transistorlogic, discrete hardware components, or any combination thereof designedto perform the functions described herein. A general purpose processormay be a microprocessor, or, any conventional processor, controller,microcontroller, or state machine. A processor also may be implementedas a combination of computing devices, for example, a combination of aDSP and a microprocessor, multiple microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration. In some implementations, particular processes, operationsand methods may be performed by circuitry that is specific to a givenfunction.

As described above, in some aspects implementations of the subjectmatter described in this specification can be implemented as software.For example, various functions of components disclosed herein or variousblocks or steps of a method, operation, process or algorithm disclosedherein can be implemented as one or more modules of one or more computerprograms. Such computer programs can include non-transitory processor-or computer-executable instructions encoded on one or more tangibleprocessor- or computer-readable storage media for execution by, or tocontrol the operation of, data processing apparatus including thecomponents of the devices described herein. By way of example, and notlimitation, such storage media may include RAM, ROM, EEPROM, CD-ROM orother optical disk storage, magnetic disk storage or other magneticstorage devices, or any other medium that may be used to store programcode in the form of instructions or data structures. Combinations of theabove should also be included within the scope of storage media.

Various modifications to the implementations described in thisdisclosure may be readily apparent to persons having ordinary skill inthe art, and the generic principles defined herein may be applied toother implementations without departing from the spirit or scope of thisdisclosure. Thus, the claims are not intended to be limited to theimplementations shown herein, but are to be accorded the widest scopeconsistent with this disclosure, the principles and the novel featuresdisclosed herein.

Additionally, various features that are described in this specificationin the context of separate implementations also can be implemented incombination in a single implementation. Conversely, various featuresthat are described in the context of a single implementation also can beimplemented in multiple implementations separately or in any suitablesubcombination. As such, although features may be described above asacting in particular combinations, and even initially claimed as such,one or more features from a claimed combination can in some cases beexcised from the combination, and the claimed combination may bedirected to a subcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. Further, the drawings may schematically depict one more exampleprocess in the form of a flow diagram. However, other operations thatare not depicted can be incorporated in the example processes that areschematically illustrated. For example, one or more additionaloperations can be performed before, after, simultaneously, or betweenany of the illustrated operations. In certain circumstances,multitasking and parallel processing may be advantageous. Moreover, theseparation of various system components in the implementations describedshould not be understood as requiring such separation in allimplementations, and it should be understood that the described programcomponents and systems can generally be integrated together in a singlesoftware product or packaged into multiple software products.Additionally, other implementations are within the scope of thefollowing claims. In some cases, the actions recited in the claims canbe performed in a different order and still achieve desirable results.

1. An apparatus for wireless communications at a first wireless communication device, comprising: a processor configured to: establish a multi-link association between the first wireless communication device and a second wireless communication device, wherein the multi-link association includes a first link between the first wireless communication device and the second wireless communication device and further includes a second link between the first wireless communication device and the second wireless communication device; and a modem configured to: obtain, from the second wireless communication device, a frame indicative that the second wireless communication device has activated one or more links of the multi-link association in accordance with data traffic associated with the first wireless communication device.
 2. The apparatus of claim 1, wherein the modem is further configured to: output a second frame that includes multi-link information, wherein the multi-link information is indicative of which of the first link and the second link are to be activated in accordance with which of the first link or the second link have the data traffic.
 3. The apparatus of claim 2, wherein the second frame is a beacon frame, and wherein the modem is further configured to: communicate multi-link capability parameters between the first wireless communication device and the second wireless communication device, wherein the multi-link capability parameters include at least a first value indicating a warm up time associated with a time for the second wireless communication device to activate the second link.
 4. The apparatus of claim 2, wherein the first link is maintained as a primary link for signaling the multi-link information for the multi-link association, and wherein the one or more links can be dynamically activated using the second frame.
 5. The apparatus of claim 2, wherein the multi-link information is indicative of which of the first link or the second link have the data traffic.
 6. The apparatus of claim 2, wherein the multi-link information is included in an aggregated control (A-Control) field of a header of the second frame.
 7. The apparatus of claim 2, wherein the first wireless communication device is an access point (AP) entity including a first AP and a second AP and the second wireless communication device is a non-AP entity including a first station (STA) and a second STA, and wherein the first link is between the first AP of the AP entity and the first STA of the non-AP entity and the second link is between the second AP of the AP entity and the second STA of the non-AP entity.
 8. The apparatus of claim 7, wherein the multi-link information includes one or more traffic identifiers (TIDs) mapped to respective ones of the first link and the second link, wherein: the processor is further configured to: delay data traffic associated with a traffic identifier (TID) mapped to the second link when the second STA is not activated; and the modem is further configured to: output the second frame via the first link to indicate that the second link is to be activated in accordance with the data traffic being mapped to the second link when the second STA is not activated.
 9. The apparatus of claim 2, wherein the multi-link information is indicative of which of the first link and the second link are to be activated in accordance with an amount of data to be sent to the second wireless communication device.
 10. The apparatus of claim 1, wherein the modem is further configured to: obtain a second frame from the second wireless communication device via the first link or the second link; and output an acknowledgement via the first link or the second link from which the frame was received.
 11. The apparatus of claim 1, wherein, to establish the multi-link association, the modem is further configured to: output, via the first link, a configuration regarding the second link, the configuration indicating one or more parameters selected from a group consisting of quality of service, bandwidth, wireless channel, transmission rate, and frequency band.
 12. The apparatus of claim 1, wherein, to establish the multi-link association, the modem is further configured to: output frames to the second wireless communication device via either the first link or the second link based on which of the first link and the second link are activated.
 13. The apparatus of claim 1, wherein the frame is a frame format selected from a group consisting of a management frame, a control frame, a data frame, a request to send (RTS), a clear to send (CTS), an acknowledgement, a power saving poll (PS-POLL) frame, a quality-of service (QoS) Null frame, and a null data packet (NDP).
 14. An apparatus for wireless communications at a first wireless communication device, comprising: a processor configured to: establish a multi-link association between the first wireless communication device and a second wireless communication device, wherein the multi-link association includes a first link between the first wireless communication device and the second wireless communication device and further includes a second link between the first wireless communication device and the second wireless communication device; and a modem configured to: output, to the second wireless communication device, a frame indicative that the first wireless communication device has activated one or more links of the multi-link association in accordance with data traffic associated with the first wireless communication device.
 15. The apparatus of claim 14, wherein the modem is further configured to: obtain, via the first link, a second frame that includes multi-link information, wherein the multi-link information is indicative of which links of the first link and the second link are to be activated in accordance with which of the first link or the second link have the data traffic.
 16. The apparatus of claim 15, wherein the first link is maintained as a primary link for receiving the multi-link information for the multi-link association, and wherein the one or more links can be dynamically activated using the second frame.
 17. The apparatus of claim 15, wherein the first wireless communication device is a non-access point (AP) entity including a first station (STA) and a second STA and the second wireless communication device is an AP entity including a first AP and a second AP, and wherein the first link is between the first AP of the AP entity and the first STA of the non-AP entity and the second link is between the second AP of the AP entity and the second STA of the non-AP entity.
 18. The apparatus of claim 17, wherein the multi-link information is indicative of the second link having data traffic, and wherein the processor is further configured to: activate the second STA to receive the data traffic for the second link.
 19. The apparatus of claim 17, wherein the multi-link information includes signaling associated with activating the second link, wherein the processor is further configured to: deactivate the first STA; switch from a first connection associated with the first STA to a second connection associated with the second STA; and activate the second STA.
 20. The apparatus of claim 14, wherein, to establish the multi-link association, the modem is further configured to: output a capability parameter indicating a warm up time associated with a time for the first wireless communication device to activate the second link.
 21. A method for wireless communication an access point (AP) multi-link device (MLD) by a first wireless communication device, comprising: establishing a multi-link association between the first wireless communication device and a second wireless communication device, wherein the multi-link association includes a first link between the first wireless communication device and the second wireless communication device and further includes a second link between the first wireless communication device and the second wireless communication device; and receiving, from the second wireless communication device, a frame indicative that the second wireless communication device has activated one or more links of the multi-link association in accordance with data traffic associated with the first wireless communication device.
 22. The method of claim 21, further comprising: transmitting a second frame that includes multi-link information, wherein the multi-link information is indicative of which of the first link and the second link are to be activated in accordance with which of the first link or the second link have the data traffic.
 23. The method of claim 22, wherein the second frame is a beacon frame, and wherein establishing the multi-link association comprises: communicating multi-link capability parameters between the first wireless communication device and the second wireless communication device, wherein the multi-link capability parameters include at least a first value indicating a warm up time associated with a time for the second wireless communication device to activate the second link.
 24. The method of claim 21, further comprising: receiving a second frame from the second wireless communication device via the first link or the second link; and transmitting an acknowledgement via the first link or the second link from which the frame was received.
 25. The method of claim 21, wherein establishing the multi-link association comprises: transmitting, via the first link, a configuration regarding the second link, the configuration indicating one or more parameters selected from a group consisting of quality of service, bandwidth, wireless channel, transmission rate, and frequency band.
 26. The method of claim 21, further comprising: delaying a communication of data from the first wireless communication device to the second wireless communication device on the second link until the second link is activated by the second wireless communication device.
 27. The method of claim 21, wherein the first wireless communication device is an access point (AP) entity including a first AP and a second AP and the second wireless communication device is a non-AP entity including a first station (STA) and a second STA, and wherein the first link is between the first AP of the AP entity and the first STA of the non-AP entity and the second link is between the second AP of the AP entity and the second STA of the non-AP entity.
 28. A method for wireless communication by a first wireless communication device, comprising: establishing a multi-link association between the first wireless communication device and a second wireless communication device, wherein the multi-link association includes a first link between the first wireless communication device and the second wireless communication device and further includes a second link between the first wireless communication device and the second wireless communication device; and transmitting, to the second wireless communication device, a frame indicative that the first wireless communication device has activated one or more links of the multi-link association in accordance with data traffic associated with the first wireless communication device.
 29. The method of claim 28, wherein the first wireless communication device is a non-access point (AP) entity including a first station (STA) and a second STA and the second wireless communication device is an AP entity including a first AP and a second AP, and wherein the first link is between the first AP of the AP entity and the first STA of the non-AP entity and the second link is between the second AP of the AP entity and the second STA of the non-AP entity.
 30. The method of claim 29, further comprising: receiving, via the first link, a second frame that includes multi-link information, wherein the multi-link information is indicative of which links of the first link and the second link are to be activated, and wherein the multi-link information is indicative of the second link having the data traffic; and activating the second STA to receive data for the second link. 